Effect of Comorbid Psychopathology on Response to Pivotal Response Treatment

Background: Extant literature on response to behavioral treatments for autism spectrum disorder (ASD) primarily highlights cognitive, social, and adaptive skill gains, with relatively little examination of what predicts these gains. Studies examining predictors of Pivotal Response Treatment (PRT) in particular are few and focus on specific behaviors (i.e., toy play or self-stimulatory behaviors).

Objectives:  Our study is one of the first to examine the predictive effects of symptoms of psychopathology on treatment response in young children with ASD.

Methods: Participants were ten 4- to 7-year-old children (2 girls) who participated in a 16-week PRT intervention. Inclusion criteria were a previous ASD diagnosis and full-scale IQ > 70 (measured by the Differential Abilities Scales-2^nd Edition). Autism Diagnostic Observation Schedule (ADOS) and Vineland Adaptive Behavior Scales-2^nd Edition (VABS-II) assessments were conducted pre- and post-treatment to measure autism symptom severity and adaptive skills. Parents also reported autism symptom severity on the Social Responsiveness Scale (SRS) and comorbid symptoms of psychopathology on the Child Behavior Checklist 1.5-5 or 6-18 (CBCL). Response to treatment was assessed by the change in total ADOS and SRS raw scores and VABS-II Adaptive Behavior Composite standard scores. Linear regression analyses examined the predictive value of pre-treatment CBCL subscale scores on these change scores, controlling for cognitive abilities. 

Results:  Pre-treatment scores on the aggression (β = -.79, p = .01), oppositional defiant disorder (β = -.64, p = .05), attention (β = -.79, p = .01), and attention deficit hyperactivity disorder (β = -.80, p = .02) CBCL subscales significantly predicted change in total ADOS scores. Scores on the withdrawn, affective, anxiety, and anxious-depressed CBCL subscales were unrelated to ADOS total score change. CBCL subscale scores at pre-treatment were unrelated to SRS and VABS-II change scores.

Conclusions:  Our results suggest that externalizing behaviors contribute to the magnitude of effect of PRT on social communication skills, with greater behavioral dysregulation at pre-treatment predicting more improvement in symptom severity as measured by the ADOS. Behaviorally dysregulated children may demonstrate a greater effect from PRT because, in addition to gaining social communication skills, they may also develop a greater capacity for behavioral regulation. Further understanding of the factors impacting treatment response may assist in identifying which treatments work best for which children, towards the goal of individualized treatment design and implementation.